1886.] 



MICROSCOPICAL JOURNAL. 



217 



5, p. 210, 1886) contains an article giving 

 an account of the various alkaloids and 

 other crystalline bodies, with notes on 

 their microscopic identification, and two 

 plates of figures illustrating the shapes of 

 the crystals. 



— The fifty-ninth meeting of the Society 

 of German Naturalists and Physicians has 

 recently been held in Berlin. It is di- 

 vided into thirty Sections, of which 

 twenty-one were more or less medical, 

 and some of the Sections had as many as 

 400 members. Professor Virchow gave 

 the introductory address. — Sci. Aniern, 

 Oct. 30, 1886. 



— The Practitioner attd N'ews (Sept. 18, 

 '86, p. 210) contains an account of the 

 death of a boy, Polymieux, from hydro- 

 phobia. The boy bitten by a dog was in- 

 oculated at Pasteur's laboratory two or 

 three days after the biting, and died on 

 the twenty-second day in spite of most 

 careful treatment under Pasteur's eyes. 



— Dr. M. D. Ewell, of Chicago, sends 

 us an extract from the Chicago Law 

 Times upon 'the limits of normal vision.' 

 In it the statement of Tidy's Legal Medi- 

 cine, p. 248, to the effect that at a distance 

 of one foot from the eye a person of nor- 

 mal sight can scarcely see an object less 

 than one twenty-fifth of an inch, is sub- 

 jected to actual test. As the result of 

 several tests, it was found that in the case 

 of most acute vision, a bit of black paper 

 I mm. square could be seen at a distance 

 of 36 inches, was seen clearly defined at 

 a distance of 5 inches and 11, and the 

 mean distance of 19 persons tested was 

 26^ \'^ for visibility, and 5^ \o'' for 

 clear definition. 



— In reply to a correspondent. Dr. P. 

 Ehrlich, in the ZeitscJir. fur. Mikr. gives 

 a method of preparing a solution of 

 hematoxylin that will keep for years. It 

 is in brief, as follows : — 



Haematoxylin solutions, as is well 

 known, rapidly decompose, with the for- 

 mation of a bluish precipitate, which by 

 dissociation of the alum is a basic lake- 

 forming alumina compound and free 

 sulphuric acid. The author attempted, 

 therefore, to prevent the formation of a 

 basic lake compound by the addition of 

 acid. The first experiment with acetic 

 acid led to most satisfactory results. 

 The mixture employed was as follows : 



Water, . . . . 100 c. c. 



Alcohol (absolute), 100 c. c. 



Glycerin, . . . 100 c. c. 



Glacial acetic acid, 10 c. c. 



Haematoxylin, . 2 grammes. 

 Alum in excess. 



The mixture ripens in the light for a 

 long time • until it acquires a saturated 

 red color, when it remains unchanged for 

 years. — H. 



— W. Migula states that the contrac- 

 tion of the protoplasm of algs and 

 desmids can be entirely prevented by 

 treating them on a cover-glass with a 

 one per cent, solution of perosmic acid. 

 After 10-20 minutes this may be re- 

 placed by potassic acetate. Desmids 

 especially are said to retain their form 

 and show the structure of their plasma 

 very well when thus treated. — H. 



CORRESPONDENCE. 



Indiana Academy of Science. 



To THE Editor : — The next meeting 

 of the Indiana Academy of Science will 

 be held at Indianapolis Dec. 29, 1886, at 

 10 A. M. 



John C. Branner, 

 O. P. Jenkins, 

 Committee on Program7ne. 

 Greencastle, Ind., Oct. 9, 1886. 

 o 



We have received from an old sub- 

 scriber a letter containing two questions : 

 I. Whether benzine can be substituted for 

 benzole in microscopic technique ? and 2. 

 Whether absolute alcohol can be made 

 readily by the use of some dehydrating 

 substance, such as quicklime ? We leave 

 the first question unanswered and invite 

 response. As to the second, absolute al- 

 cohol — that is, 100% alcohol — is not neces- 

 sary for paraffin imbedding, but, on the 

 other hand, 95%' will not answer. The 

 exact percentage of water which may be 

 present we cannot say, but our experience 

 shows that alcohol with 55'o of water pres- 

 ent— that is the commercial article— will not 

 answer, though if the percentage be only 

 2 or 3, or possibly 4, of water, it can appar- 

 ently be used as well as the absolute. We 

 have tried dehydrating with quicklime and 

 with copper sulphate on a small scale, but 

 it has never proved a success. The last 

 trace of alcohol will not be removed by 

 turpentine unless the alcohol be of high 

 proof, and we have never been able to use 

 other than a very high proof alcohol, higher 

 than any commercial alcohol we have ever 

 found. We know of laboratories where 

 absolute alcohol is made for histological 

 work, copper sulphate being preferred, but, 

 i unless the amount to be used is very con- 



